PowerScale OneFS 9.2.1.0 CLI Administration Guide

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Snapshot-based incremental backups

You can implement snapshot-based incremental backups to increase the speed at which these backups are performed.

During a snapshot-based incremental backup, OneFS checks the snapshot taken for the previous NDMP backup operation and compares it to a new snapshot. OneFS then backs up all files that was modified since the last snapshot was made.

If the incremental backup does not involve snapshots, OneFS must scan the directory to discover which files were modified. OneFS can perform incremental backups significantly faster if the change rate is low.

You can perform incremental backups without activating a SnapshotIQ license on the cluster. Although SnapshotIQ offers a number of useful features, it does not enhance snapshot capabilities in NDMP backup and recovery.

Set the BACKUP_MODE environment variable to SNAPSHOT to enable snapshot-based incremental backups. If you enable snapshot-based incremental backups, OneFS retains each snapshot taken for NDMP backups until a new backup of the same or lower level is performed. However, if you do not enable snapshot-based incremental backups, OneFS automatically deletes each snapshot generated after the corresponding backup is completed or canceled.

NOTE A snapshot-based incremental backup shares the dumpdates entries in dumpdates database along with the other level-based backups. Therefore, make sure that you do not run snapshot-based backups and regular level-based backups in the same backup paths. For example, make sure that you do not run a level 0 backup and snapshot-based incremental backup in the same backup path or vice versa.

After setting the BACKUP_MODE environment variable, snapshot-based incremental backup works with certain data management applications (DMAs) as listed in the next table.

Table 1. DMA support for snapshot-based incremental backups
DMA	DMA-integrated
Symantec NetBackup	Enabled only through an environment variable.
Networker	Enabled only through an environment variable.
Avamar	Yes
CommVault Simpana	Enabled only through a cluster-based environment variable.
Tivoli Storage Manager	Enabled only through a cluster-based environment variable.
Symantec Backup Exec	Enabled only through a cluster-based environment variable.
NetVault	Enabled only through a cluster-based environment variable.
ASG-Time Navigator	Enabled only through a cluster-based environment variable.